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APU System
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Terms in this set (22)
- Electrical and Bleed Air
What is the APU used for?
- It's own dedicated FADEC
What monitors and controls the APU?
- BATT 2 powers the APU START bus
- BATT 1 powers the FADEC and EICAS for monitoring
How are the batteries used for APU start?
- Right fuel tank
- Left fuel tank through the crossfeed valve
What is the fuel source for the APU?
- Batteries 'ON' only DC fuel pump
- AC Powered aircraft AC fuel pump 2
- Right engine running Ejector fuel pump
What fuel pump is used for the APU start?
- APU icon is available on the ELEC synoptic page
When does the APU electrical and pneumatic loading become available?
- Yes
Will the APU shutdown automatically if the APU fails to start within the normal start cycle period?
- Initiates a normal APU shutdown
- 1 minute cool down followed by a spool down period
- Pneumatics removed immediately and electrical power is removed after the 1 minute cool down.
What does moving the APU selector knob to OFF do?
- No
Can the APU pneumatics be used during the cool down period?
- Yes
Can the APU electrical power be used during the cool down period?
- Yes, just turn the APU master switch back to ON
If you need the APU 50 seconds into shutdown is there a way to get its use back?
- Yes, by moving the MASTER switch back to ON before the 1 minute cool down is over.
Can the APU shutdown be cancelled?
- APU EMER STOP button
- No 1 minute cool down period.
How can the APU be shutdown immediately?
- Ground - all conditions
- Flight - Overspeed
- Underspeed
- FADEC critical fault
When will automatic shutdown of the APU occur?
- an APU fire is detected
When do we get the red bar on the APU EMER STOP button?
- The APU fuel shutoff valve closes and the APU will shutdown with no cooling period. A white stripe illuminates on the button.
What happens when the APU EMER STOP button is pushed?
- No
Does the cool down period apply to the APU EMER STOP button?
Right Tank
In normal operations on the ground with the APU running it would be normal to see the fuel unbalanced with less fuel in which tank?
- 15,000 feet
What is the maximum altitude for operation of the APU bleed?
- 33,000 feet
What is the maximum altitude for APU operations?
- 30,000 feet
What is the maximum altitude for APU start?
- 21,000 feet
Up to what altitude may the APU assist in engine start?
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ENGINEERING
A piston–cylinder device contains 50 kg of water at 250 kPa and $25 ^ { \circ } \mathrm { C }$. The cross-sectional area of the piston is 0.1 m^2. Heat is now transferred to the water, causing part of it to evaporate and expand. When the volume reaches 0.2 m^3, the piston reaches a linear spring whose spring constant is 100 kN/m. More heat is transferred to the water until the piston rises 20 cm more. Using an appropriate software, investigate the effect of the spring constant on the final pressure in the cylinder and the boundary work done. Let the spring constant vary from 50 kN/m to 500 kN/m. Plot the final pressure and the boundary work against the spring constant, and discuss the results.
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